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Migrate VerticalWhitespaceRule from SourceKit to SwiftSyntax (#6103)

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* Migrate VerticalWhitespaceRule from SourceKit to SwiftSyntax

* Adds tests for new horizontal whitespace behavior
This commit is contained in:
Matt Pennig
2025-06-19 16:31:51 -05:00
committed by GitHub
parent 6d5af5f924
commit 1e25cf6be6
4 changed files with 122 additions and 105 deletions
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CHANGELOG.md
+3
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@@ -22,6 +22,9 @@
and fewer false positives.
[JP Simard](https://github.com/jpsim)
* Migrate `vertical_whitespace` rule from SourceKit to SwiftSyntax for improved performance.
[Matt Pennig](https://github.com/pennig)
### Bug Fixes
* Improved error reporting when SwiftLint exits, because of an invalid configuration file
Source/SwiftLintBuiltInRules/Rules/RuleConfigurations/VerticalWhitespaceConfiguration.swift
+9
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@@ -4,8 +4,17 @@ import SwiftLintCore
struct VerticalWhitespaceConfiguration: SeverityBasedRuleConfiguration {
typealias Parent = VerticalWhitespaceRule
static let defaultDescriptionReason = "Limit vertical whitespace to a single empty line"
@ConfigurationElement(key: "severity")
private(set) var severityConfiguration = SeverityConfiguration<Parent>(.warning)
@ConfigurationElement(key: "max_empty_lines")
private(set) var maxEmptyLines = 1
var configuredDescriptionReason: String {
guard maxEmptyLines == 1 else {
return "Limit vertical whitespace to maximum \(maxEmptyLines) empty lines"
}
return Self.defaultDescriptionReason
}
}
Source/SwiftLintBuiltInRules/Rules/Style/VerticalWhitespaceRule.swift
+105 -104
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@@ -1,146 +1,147 @@
import Foundation
import SourceKittenFramework
import SwiftSyntax
private let defaultDescriptionReason = "Limit vertical whitespace to a single empty line"
struct VerticalWhitespaceRule: CorrectableRule {
@SwiftSyntaxRule(explicitRewriter: true, correctable: true)
struct VerticalWhitespaceRule: Rule {
var configuration = VerticalWhitespaceConfiguration()
static let description = RuleDescription(
identifier: "vertical_whitespace",
name: "Vertical Whitespace",
description: defaultDescriptionReason + ".",
description: VerticalWhitespaceConfiguration.defaultDescriptionReason,
kind: .style,
nonTriggeringExamples: [
Example("let abc = 0\n"),
Example("let abc = 0\n\n"),
Example("/* bcs \n\n\n\n*/"),
Example("// bca \n\n"),
Example("class CCCC {\n \n}"),
],
triggeringExamples: [
Example("let aaaa = 0\n\n\n"),
Example("struct AAAA {}\n\n\n\n"),
Example("class BBBB {}\n\n\n"),
Example("class CCCC {\n \n \n}"),
],
corrections: [
Example("let b = 0\n\n\nclass AAA {}\n"): Example("let b = 0\n\nclass AAA {}\n"),
Example("let c = 0\n\n\nlet num = 1\n"): Example("let c = 0\n\nlet num = 1\n"),
Example("// bca \n\n\n"): Example("// bca \n\n"),
Example("class CCCC {\n \n \n \n}"): Example("class CCCC {\n \n}"),
] // End of line autocorrections are handled by Trailing Newline Rule.
)
}
private var configuredDescriptionReason: String {
guard configuration.maxEmptyLines == 1 else {
return "Limit vertical whitespace to maximum \(configuration.maxEmptyLines) empty lines"
}
return defaultDescriptionReason
}
private extension VerticalWhitespaceRule {
final class Visitor: ViolationsSyntaxVisitor<ConfigurationType> {
override func visit(_ token: TokenSyntax) -> SyntaxVisitorContinueKind {
// The strategy here is to keep track of the position of the _first_ violating newline
// in each consecutive run, and report the violation when the run _ends_.
func validate(file: SwiftLintFile) -> [StyleViolation] {
let linesSections = violatingLineSections(in: file)
guard linesSections.isNotEmpty else {
return []
if token.leadingTrivia.isEmpty {
return .visitChildren
}
var consecutiveNewlines = 0
var currentPosition = token.position
var violationPosition: AbsolutePosition?
func process(_ count: Int, _ offset: Int) {
for _ in 0..<count {
if consecutiveNewlines > configuration.maxEmptyLines && violationPosition == nil {
violationPosition = currentPosition
}
consecutiveNewlines += 1
currentPosition = currentPosition.advanced(by: offset)
}
}
for piece in token.leadingTrivia {
switch piece {
case .newlines(let count), .carriageReturns(let count), .formfeeds(let count), .verticalTabs(let count):
process(count, 1)
case .carriageReturnLineFeeds(let count):
process(count, 2) // CRLF is 2 bytes
case .spaces, .tabs:
currentPosition += piece.sourceLength
default:
if let violationPosition {
report(violationPosition, consecutiveNewlines)
}
violationPosition = nil
consecutiveNewlines = 0
currentPosition += piece.sourceLength
}
}
if let violationPosition {
report(violationPosition, consecutiveNewlines)
}
return .visitChildren
}
return linesSections.map { eachLastLine, eachSectionCount in
StyleViolation(
ruleDescription: Self.description,
severity: configuration.severityConfiguration.severity,
location: Location(file: file.path, line: eachLastLine.index),
reason: configuredDescriptionReason + "; currently \(eachSectionCount + 1)"
)
private func report(_ position: AbsolutePosition, _ newlines: Int) {
violations.append(ReasonedRuleViolation(
position: position,
reason: configuration.configuredDescriptionReason + "; currently \(newlines - 1)"
))
}
}
private typealias LineSection = (lastLine: Line, linesToRemove: Int)
final class Rewriter: ViolationsSyntaxRewriter<ConfigurationType> {
override func visit(_ token: TokenSyntax) -> TokenSyntax {
var result = [TriviaPiece]()
var pendingWhitespace = [TriviaPiece]()
var consecutiveNewlines = 0
private func violatingLineSections(in file: SwiftLintFile) -> [LineSection] {
let nonSpaceRegex = regex("\\S", options: [])
let filteredLines = file.lines.filter {
nonSpaceRegex.firstMatch(in: file.contents, options: [], range: $0.range) == nil
}
func process(_ count: Int, _ create: (Int) -> TriviaPiece) {
let linesToPreserve = min(count, max(0, configuration.maxEmptyLines + 1 - consecutiveNewlines))
consecutiveNewlines += count
guard filteredLines.isNotEmpty else {
return []
}
if count > linesToPreserve {
self.numberOfCorrections += count - linesToPreserve
}
let blankLinesSections = extractSections(from: filteredLines)
// filtering out violations in comments and strings
let stringAndComments = SyntaxKind.commentAndStringKinds
let syntaxMap = file.syntaxMap
let result = blankLinesSections.compactMap { eachSection -> (lastLine: Line, linesToRemove: Int)? in
guard let lastLine = eachSection.last else {
return nil
}
let kindInSection = syntaxMap.kinds(inByteRange: lastLine.byteRange)
if stringAndComments.isDisjoint(with: kindInSection) {
return (lastLine, eachSection.count)
if linesToPreserve > 0 {
// We can still add this piece, even if we adjusted its count lower.
// Pull in any pending whitespace along with it.
result.append(contentsOf: pendingWhitespace)
result.append(create(linesToPreserve))
pendingWhitespace.removeAll()
} else {
// We're now in violation. Dump pending whitespace so it's excluded from the result.
pendingWhitespace.removeAll()
}
}
return nil
}
return result.filter { $0.linesToRemove >= configuration.maxEmptyLines }
}
private func extractSections(from lines: [Line]) -> [[Line]] {
var blankLinesSections = [[Line]]()
var lineSection = [Line]()
var previousIndex = 0
for (index, line) in lines.enumerated() {
let previousLine: Line = lines[previousIndex]
if previousLine.index + 1 == line.index {
lineSection.append(line)
} else if lineSection.isNotEmpty {
blankLinesSections.append(lineSection)
lineSection.removeAll()
for piece in token.leadingTrivia {
switch piece {
case .newlines(let count):
process(count, TriviaPiece.newlines)
case .carriageReturns(let count):
process(count, TriviaPiece.carriageReturns)
case .carriageReturnLineFeeds(let count):
process(count, TriviaPiece.carriageReturnLineFeeds)
case .formfeeds(let count):
process(count, TriviaPiece.formfeeds)
case .verticalTabs(let count):
process(count, TriviaPiece.verticalTabs)
case .spaces, .tabs:
pendingWhitespace.append(piece)
default:
// Reset and pull in pending whitespace
consecutiveNewlines = 0
result.append(contentsOf: pendingWhitespace)
result.append(piece)
pendingWhitespace.removeAll()
}
}
previousIndex = index
}
if lineSection.isNotEmpty {
blankLinesSections.append(lineSection)
}
return blankLinesSections
}
func correct(file: SwiftLintFile) -> Int {
let linesSections = violatingLineSections(in: file)
if linesSections.isEmpty {
return 0
}
var indexOfLinesToDelete = [Int]()
for section in linesSections {
let linesToRemove = section.linesToRemove - configuration.maxEmptyLines + 1
let start = section.lastLine.index - linesToRemove
indexOfLinesToDelete.append(contentsOf: start..<section.lastLine.index)
}
var correctedLines = [String]()
var numberOfCorrections = 0
for currentLine in file.lines {
// Doesn't correct lines where rule is disabled
if file.ruleEnabled(violatingRanges: [currentLine.range], for: self).isEmpty {
correctedLines.append(currentLine.content)
continue
// Pull in any remaining pending whitespace
if !pendingWhitespace.isEmpty {
result.append(contentsOf: pendingWhitespace)
}
// removes lines by skipping them from correctedLines
if Set(indexOfLinesToDelete).contains(currentLine.index) {
// reports every line that is being deleted
numberOfCorrections += 1
continue // skips line
}
// all lines that pass get added to final output file
correctedLines.append(currentLine.content)
return super.visit(token.with(\.leadingTrivia, Trivia(pieces: result)))
}
// converts lines back to file and adds trailing line
if numberOfCorrections > 0 {
file.write(correctedLines.joined(separator: "\n") + "\n")
}
return numberOfCorrections
}
}
Tests/BuiltInRulesTests/VerticalWhitespaceRuleTests.swift
+5 -1
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@@ -9,7 +9,10 @@ final class VerticalWhitespaceRuleTests: SwiftLintTestCase {
// Test with custom `max_empty_lines`
let maxEmptyLinesDescription = VerticalWhitespaceRule.description
.with(nonTriggeringExamples: [Example("let aaaa = 0\n\n\n")])
.with(triggeringExamples: [Example("struct AAAA {}\n\n\n\n")])
.with(triggeringExamples: [
Example("struct AAAA {}\n\n\n\n"),
Example("class BBBB {\n \n \n \n}"),
])
.with(corrections: [:])
verifyRule(maxEmptyLinesDescription,
@@ -23,6 +26,7 @@ final class VerticalWhitespaceRuleTests: SwiftLintTestCase {
.with(corrections: [
Example("let b = 0\n\n↓\n↓\n↓\n\nclass AAA {}\n"): Example("let b = 0\n\n\nclass AAA {}\n"),
Example("let b = 0\n\n\nclass AAA {}\n"): Example("let b = 0\n\n\nclass AAA {}\n"),
Example("class BB {\n \n \n↓ \n let b = 0\n}\n"): Example("class BB {\n \n \n let b = 0\n}\n"),
])
verifyRule(maxEmptyLinesDescription,